Electrical circuits requiring high power handling capability while operating at high frequencies such as radio frequencies, S-band and X-band have in recent years become more prevalent. Because of the increase in high power, high frequency circuits there has been a corresponding increase in demand for transistors that are capable of reliably operating at radio frequencies and above while still being capable of handling higher power loads.
Metal-semiconductor field effect transistors (MESFETs) have been developed for high frequency applications. The MESFET construction may be preferable for high frequency applications because only majority carriers carry current. The MESFET design may be preferred over current MOSFET designs because the reduced gate capacitance permits faster switching times of the gate input. Therefore, although all field-effect transistors utilize only majority carriers to carry current, the Schottky gate structure of the MESFET may make the MESFET more desirable for high frequency applications.
In particular, silicon carbide (SiC) MESFETs are used in commercial communication applications as well as in high power amplifiers for defense. In these applications, as well as others, the high gain, low distortion, and high efficiency provided by the SiC MESFET are desirable. However, manufacturing costs of SiC MESFETs may be higher than the costs of competing technologies, such as silicon devices.